Diaphragm for acoustic instruments.



T. H. REED.

DiAPHRAGM F08 Acoussc lNSRUMENTs.

APPLICATIQN FILED MAY 4. 1916* Patented Oct. 15, 1918.

THOMAS HERBERT REED, OF NEWARK, NEW JERSEY.

I DIAPHRAGM EOR ACOUSTIC INSTRUMENTS.

Specification of Letters Patent.

Patented Oct. 15, 1918.

Application tiled May 4, 1916. Serial No. 95,445.

T 0 all w/:o//zI it may concern.'

Be it known that I, THOMAS HERBERT REED, a citizen of the United States, residing at Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Diaphragms for Acoustic Instruments, of which the following is a specification. y

This invention relates to diaphragms for acoustic instruments and it comprises a coinposite diaphragm having a base of animal skin and one or more reinforcing relatively thin skins, the reinforcing skins advantageously beineF from a different animal than the skin of the base and also of a different diameter; and it further comprises a composite diaphragm built up of two or more animal skins, advantageously of different thicknesses and different diameters and reinforced by means of fabric and the like which may be placed between the base skin and the other skins, andthe reinforcing skins or both. The invention further comprises a diaphragm composed 0f animal hide which is rendered stiff, strong and durable, impervious to moisture by means of a water proof coating, for instance, a coating of collodion or a solution of pyroxylin in a suitable solvent; a'll as more fully hereinafter set forth and as claimed.

Heretofore in this art mica, fiber, paper and metal diaphragms .have been proposed and used, but they are Subj ect to certain disadvantages which it is the object of my present invention to overcome. The mica and metal diaphragms, whether the metal be corrugated or plain produce metallicr sounds which are not pleasing and which interfere with the perfect rendition of the 'recorded sounds. Furthermore' such diaph'ragms do not transmit the low registers as prominently as the high and they are at times, so sensitive as to result in transmitting the surface nises or scratch of the needle through the amplifier.

The fiber and paper diaphragms muie the sounds to a detrimental degree and the do not uniformly transmit from the recor the different pitches of the notes. At times the fiber' and paper diaphragms seem to render fiat tones.

The provision of an inexpensive and durable diaphragm overcoming the above disadvantages has long been a desideratum in this art. My improved diaphragm obviates the disadvantages'V inherentin other types.

In the accompanying drawings showing several forms of a specific embodiment of my invention, Figure 1 is a transverse section through a sound box showing my diaphragm in position; Fig. 2 is a vertical section through one form of the diaphragm;` Fig. 3 is a front View thereof partly in section; Fig. 4 is a vertical section through' another form of the diaphragm omittin the fabric between the base and the two reinforcing skin layers; and Fig. 5 is a fragmentary sectional views illustrating a portion of the completed diaphragm.

In the drawings, 1 indicates the sound box, the interior walls of which are threaded as at 2. Plate 3, having integral sleeve 4 with pin 5 for attachment to tone arm, is placed over the diaphragm 6 and is forced into position to hold the diaphragm in place by means of the externally threaded rin 7. The gaskets 8 and 9 may be employed. he sound box per se is not claimed in this .application.

The diaphragm 6 is composed of a base l0 formed from a hide which has been aged; I have found cowhide to be particularly advantageous although other similar hides may be used. The cowhide is covered with a solution of water-proof varnish 11 preferably containing pyroxylin. This coating renders the outer hide impervious to moisture, stiffens and reinforces it, and seems to have a tendency to tension thebase. The tensioning is probably due to the fact that the pyroxylin coating shrinks as the solvent evaporates and, since the coating is continuousgthroughout the surfaces and edges of the base both when originally applied and after the solvent is evaporated, it is possible that a shrinking or drawing action results from evaporation.

The base 10 is further reinforced by means of another animal skin or hide 12 on one side and 13 on the other. One ofthese hides, for instance 12, may be of less diameter than the base` 10 and the other of these hides, for instance 13, may be of less diameter than the hide 12; and advantageously the hides 12 and 13 are of different texture from the base l() and from ea'ch other. In use I have found -a very satisfactory diaphragm may be made by using cowhide as a base 10, sheep skin as the reinforcing member. 12 and calf skin as the reinforcing member 13, although these may be interchanged if desired.

The skins 12 and 13 are attached to the base l0 by means of suitable glue or glue and varnish, and if desired, a piece of fabric such, for instance, as cheese-cloth 14 may be interposed between the base and one or both of the reinforcing hides 12 and 13. When a particularly rigid diaphragm is desired, I use the cheese-cloth or other fabric as indicated. However, as stated, I may dispense with it.

A fabric of cheese-cloth or other suitable material 15 is attached by means of varnish or other suitable adhesives over the reinforc- -ing hides 12 and 18, and ifA desired for the purpose of appearances, a section of suitably colored cloth is attached covering the .whole composite diaphragm.

While I do not confine myself to any theory as to the reasons for the im rovement resultin from this compoun diaphragm, I believe that it is due to two important particulars. First, to the use of the animal hide or skin, suitably reinforced, either by the collodion or the other hides or cheese-cloth; and second, to the arrangement whereby the center of the diaphragm is thicker than the periphery, this resulting in securing a uniform vibratlon throughout the whole area. The periphery is, ofcourse, confined in the sound box and is therefore under a greater tension than the center. By making the center relatively thick as compared to the peri hery, I secure a more or less uniform tension throughout the whole diaphragm, and this tension is gradual from the periphery to the center when the diaphragm is'not confined in the sound box.

I may, of course, omit the silk covering and color 'the outer hides or the cheesecloth, but this would give the diaphragm a stepped appearance. I may omit one or the other of the hides 12 and 13 or I may omit the cheese-cloth or other fabric 14 and 15.

I believe I am thel first to use reinforced animal hide for diaphragm in a talking machine, and particularly a diaphragm rendered stili, strong and durable by means of reinforcement either in the nature of a water-proof material or other means; and I believe I am the first to use compound diaphragm composed of a plurality of animal skins of different sizes.

The particular hides I have found advantageous are aged and new cowhide for the base, aged and new llama, slunk skin and new or aged calfskin, the cowhide forming the base and the calf and slunk skins the reinforcing hides. I may use glue, shellac, varnish or other adhesives for attaching the skins one to another either direct or through the medium of cheese-cloth or other fabric; and I may use other water-proof coating than collodion for the' base. Furthermore, if desired, I may water-proof the reinforcing hides and the whole diaphragm as Well as the base hide.

T o make the complete diaphragm shown in Fig. 1, (a specific embodiment of my invention) I first cut aged cowhide to diaphragm size and then coat both sides and the edge with collodion to make it impervious to moisture and to strengthen it. The so-coated base is then dried, preferably at a temperature from 200o to 300 F. and it is then lined on both sides with fabric, preferably cheese-cloth for stiienin it. I then coat both sides of this base wit shellac and on one side I place a calf skin of less diameter than the base. This calf skin is thinner than cowhide. On the other side I place a section of sheep skin, advantageously of less diameter than the base and also of less diameter than the calf skin. This sheep skin is thinner than calf skin. I then coat the composite diaphragm thus made with lue or varnish and bake the same for a ew hours at a temperature of about 200 F.l If desired, I then coat the calf skin and the sheep skin with cheesecloth causing it to adhere through means of shellac or glue and I then cover the whole diaphragm on both sides with thin cloth, preferably silk 16. The silk is for the purpose of appearances.

The needle-holdin attached by means of What I claim is 1. A diaphragm comprising a base of animal hide and reinforcing means one on each side of said base, said reinforcing means being of less diameter thanthe base, and one of said reinforcing layers being of less diameter than the other.

2. A diaphragm comprising a base of animal skin, and la. ers of reinforcing means on either side of said base, the reinforcing layer on one side being of less thickness than the reinforcing layer on the other side.

3.`A"d1aphragm comprisin a base of animal skin and layers of rein orcing means on either side, the reinforcing layer on one side being of sli htly less diameter than the base andY of slig tly less thickness, and the reinforcing layer on the other side being of less diameter and less thickness than said first layer.

4. A diaphragm comprising a plurality arm 17 may then be a screw 18 and nut 19.

of sections of animal skins reinforced by means of fabric.

5. A diaphragm comprising a plurality of united sections of animal skins of different dimensions and a covering for all of them of substantially the same diameter as the largest skin.

6. A diaphragm comprisin a base of animal skin, having a coatlng o waterproofing material, and layers of reinforcing means on either side, said reinforcing means comprising animal skins also having a coating of waterproofing material, the reinforcing layers and base and a covering for all of layer on one side being of slightly less dithem, of substantially the same diameter as ameter than the base and of slightly less the largest skin. 10

thickness, and the reinforcingl layer on the In testimony whereof I affix my signature other side being of less diameter and less hereto.

thickness than said first layer, Waterproofecl fabric interposed between each of said THOMAS HERBERT REED.

Copies loi this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

